So What Exactly is Zone 2?

Ah heart rate zones. I admit, I’ve been using my heart rate monitor frequently yet I am still not doing much with the data. I’ve been frustrated and confused with the whole thing and kind of just went into auto-pilot of using my Garmin heart rate monitor but not actually paying attention to it. The main reason that I got my V02 max test done back in December was so that I could get my training heart rate zones. I heard that I should race the Ironman in heart rate zone 2 and no higher, otherwise my stomach may shut down or I won’t have any energy left for the run.

However, my VO2Max results were a little unusual, according to the test proctor, a triathlon coach named Ken. My VO2Max is 95% of maximum heart rate (which is also high – 195) as compared to the average athlete’s 85-88%. Basically this means that I can sustain hard efforts for longer than a typical person (according to Ken anyway).  Maximum heart rate and VO2Max are the basis for the calculation of heart rates zones. Based on my data, my Zone 2 ended up at a 150-170 range. After using my Garmin’s heart rate monitor for a couple of weeks, I was finding that it was difficult for me to get my average heart rate  into Zone 2 on easy rides and on my super hard Sufferfest intervals, it was only getting up to the low 170s. I was kind of confused and began to wonder if my zones were incorrect. I e-mailed Ken and he sent me over a new set of zones based on Vo2Max being 88% of Max HR, despite the fact that my test showed otherwise. My new Zone 2  was 140-157 bpm or 140-157 watts and my peak high end Zone 5 was 174. However, since I use a power meter on the trainer, I realized that these also cannot be accurate. Usually my 80% effort during a Sufferfest DVD is about 200-220 and my 70% effort (ie around LT) is 175-195. “Easy” on the trainer is more like 160. So there is no way that a Zone 5 of 174 works since I’ll often max out at 250 or more.

So basically my data wasn’t matching up. Since the number 150 ended up in both sets of Zone 2 that Ken sent me, I decided to use that as a guide for rides. Going up hills my heart rate can get close to 170 and in general it stays between 145-155. However, during warm-ups and stop light sections, it can get down to 120. I was complaining to Mike one night about my heart rate zones not matching (which made me laugh thinking of Lauren’s blog post about surviving through training for an Ironman with your significant other – “I don’t give a sh*t what your heart rate was this morning!”) and he said “zone 2 is big.”

Zone 2 is Big (and not as easy as I thought)

Then it clicked. Zone 2 is a big zone. 150 should feel different than 170. Maybe the reason I have a hard time coming back from a long ride with a total average heart rate in Zone 2 is because there are so many stop lights and stop signs. When I’m actually cruising at a good, heart pumping pace, my heart rate IS in Zone 2. And, as Mike pointed out, when I’m sprinting during a Sufferfest, even though my HR only gets up to 175, it really doesn’t have time to get even higher since I only stay in that zone for 15 or 20 seconds. If I had more time at this pace, I’m sure it would skyrocket to the 180s, which is Zone 4. This was also confirmed by Joe Fiel in Going Long who mentions in the book that heart rate training during intervals is difficult since the heart rate takes time to catch up.  He recommends using perceived effort with intervals.

After re-reading the guide that Ken gave me after my V02 Max test, I realized that Zone 1’s description is “easy relaxed pace, gentle breathing” and it should be used for “active recovery” and executed “1-5 days a week, 20-240 minutes or more per session.” No wonder when I am cruising the coast on my bike and stopping at stop signs,  I’m still in Zone 1. I had it in my mind that Zone 1 was literally the effort it takes to walk or sit on the couch. I practically thought I was in Zone 1 as I type this sitting at the computer.  However, according to Ken, it’s totally normal to do a ride in Zone 1. Zone 2, on the other hand, has a description of “aerobic endurance, comfortable pace, deeper breathing” and is used for “aerboic intervals” and should be executed “2-3 days a week, 30-120 minute+. So Zone 2 isn’t as easy as I thought.

LiveStrong.com cleared it up a bit for me as well:

Zone 1- Most of your training — and some of the race — should be done in Zone 1, or between 50 and 70 percent of your maximum heart rate.

Zone 2 – About a quarter of your training time and most of the race should be done between 70 and 80 percent of your MHR. During training, you’ll use this pace to do longer speed work and your easier long runs, and this will be your “base” pace for the race itself. Zone 2 is still aerobic, using your fat stores for energy — but it is just on the border of your anaerobic threshold. Going any faster during the race will force your body to use your carb stores for fuel, and they will be depleted within a couple of hours.

So there you have it. I think that my original zones are right – despite being high. While reading Chris McCormick’s Book “I’m Here to Win” he mentioned not letting his HR get above 140 during the race. For me, 140 is in Zone 1. I’ve read other accounts of Ironmen racing with an HR no higher than 140. It does intimidate me a little bit that my heart rate is a bit higher than average, since I could risk going out too hard at the race, but I think that it’s legit. Running HR zones are about 10 bpm higher than cycling, meaning Zone 2 would be 160-180 for me. Seems high, but I ran 26.2 miles at the Surf City marathon with an average HR of 175. I also did a 18 mile training run with an average HR of 185.

Of course, I’ll keep comparing HR and perceived effort to figure out exactly where I should be for the race and adjust if necessary.

Why Do I Even Care What Zone 2 Is!?

If you aren’t familiar with heart rate zone training, the reason for knowing and staying within your desired zones is important for 2 reasons:

1) If you stay within HR Zone 2 during a race, you will burn more calories from fat (unlimited supply) rather than calories from carbohydrate (limited supply) and therefore reduce your chances of “bonking.”  Staying within this zone is imperative to maintain energy for the marathon that follows.

2) If you know your zones, you ensure that your easy training days are easy and  your hard training days are hard. Although perceived effort is also a great way to guide your way through a recovery or tempo workout, having data to support your perception is useful. Sometimes we think we’re going easy but our body doesn’t agree. And sometimes we think we’re pushing it but we’re not. Using your heart rate to train is useful for keeping it all in check.

Although both of these reasons are important to me, the main reason I care about my zones is for the Ironman itself. I want to have a good race and ideally I’d like to spend most of the marathon running, not walking or puking or on in a porta potty.

Do you agree with my perception on what zone 2 is? Any advice on heart rate training would be appreciated!